I think you might want something like this:

DECLARE @orders TABLE

(

OrderNo INT,

ReceiptDate DATE

);

SELECT

*

FROM

@orders AS O

WHERE

EXISTS ( SELECT

1

FROM

@orders AS O2

WHERE

O2.OrderNo = O.OrderNo

HAVING

MAX(O2.ReceiptDate) >= DATEADD(MONTH, -6, CURRENT_TIMESTAMP) );

I'm not saying there isn't a better way and since you are in the 2014 forum you might be able to do something with the windowing functions.